willis



B. D. WILLIS. AUTOMATIC TELEPHONE SYSTEM.

' APPucATloN man MAR. l. me.

B. D. WILLIS.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION mw MAR. 1. 191e.

1,315,440. Patent-ed Sept. 9, 1919;

2 SHEETS-SHEET '2.

ily-@wg JW HUD!" gay UNITED STATES PATENT OFFICE.

BERNARD D. WILLIS, OF CHICAGO, ILLINOIS, ASSIGNOR TO AUTOMATIC ELECTRICCOMPANY, OF'CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

Original application iled May 2, 1914, Serial No. 835,817.

Patent No. 1,280,609, dated October 1, 1918. Divided and thisapplication filed March 1, 1916.

To all whom-it may concern:

Be it known that I, BERNARD D. VVILLI's, a citizen of the United Statesoi America, and resident of Chicago, Cook county, Illia nois, haveinvented certain new and useful Improvements in Automatic TelephoneSystems, of which the following is a specification.

My invention relates to improvements in automatic telephone systems-thatis, systems in which one or more switches are employed for establishinglconnection between subscribers lines.

One of the Jfeatures of my invention is the provision oit an improvedconnector for use especially in connection with a toll operators board,which connector, when it is op erated to connect with a busyl line,locks on said line without establishing` a talking conneciion therewith,and as soon as the dcsired line is again idle a signal is given to thetoll operator and the talking connection is completed with the desiredline. In this manner the establishment of a connection is greatlyexpedited, as the toll connection is established as soon as the desiredline becomes idle and without the necessity o1 the toll operator againsetting up the connection.

This and other objects of my invention will be more clearly understoodby reference to the accompanying drawings, in which I have illustratedmy invention in connection with automatic switches of well-known types,together with a certain well-known form oi manual apparatus. Myinvention is, however, equally as well adapted for use with other formsof automatic switches and cord circuits, and the present system ismerely for the purpose of illustrating one specific embodiment of m iinvention.

Figure 1 shows the terminal conductors of a toll line ending in a jack,7'2 at a toll board, an operators cord circuit C and a selector switchcircuit 'for use with the operators cord circuit.

Fig, 2 shows diagrammatically a connector for completing the tollconnection to an automatic substation.

Although reference has been made to automatic apparatus and to a manualapparatus, it is to be understood that this does not mean that themanual part of the system is necessarily a separate and distant exchangeSpecification of Letters Patent.

` board.

AUTOMATIC TELEII-IONE SYSTEM.

Patented Sept. 9, 1919.

Renewed February 23, 1918, Serial No. 218,898. Serial in itself. It maybe simply a manual switchboard, which is usually installed in automaticexchanges for the purpose of handling long distance or toll calls.

In Fig. 1 I have shown a trunk line 53-5-1 which terminates in the usualanswering jack jg and multiple jacks at the toll This trunk line isprovided with the usual line relay controlling the line lamp 57 andcut-off relay 56.

The operators cord circuit O resembles the usual cord circuit in manualsystems in that it comprises an answering plug p2, a calling plug p,calling` and answering supervisory lamps 59 and 60 and suitable relaysfer controlling the circuits thereof. The cord circuit is also providedwith a calling device (which is herein represented by a pair of impulsesprings), a busy supervisory lamp 61 (which will be hereinafter morefully explained), a ringing current generator R and the necessary keysfor controlling the operations of the said cord circuit.

The trunk lines which lead from the manual switch-board to the selectorF terminate in multiple jacks j* on the manual switchboard. The sleeveconductors of the jacks y" are connected to battery through a relay 62which controls the circuit of a visual busy signal 63 associated witheach multiple jack.

The toll selector F is of the general type of selector switch shown inU. S. Letters Patent No. 815,321, granted March 13, 1906 toKeitli,Eiickson and Erickson, except that the so-called side switch isomitted and the circuits modified tov adapt it to operate in a system inwhich it is controlled by impulses delivered over two sides of the linein series, as shown in British Patent No. 10,376 or' 1912, and with theaddition of a set of springs 158, 176 and 180 that are operated upon theeleventh rotary step of the rotary magnet, the function of which is togive the calling operator a busy signal if all the trunks on any onelevel of the selector banks are busy and to prevent the said selectorswitch from further operation.

The toll connector M is of the same general type of connectoi` switch asthat dis closed in U. S. Letters Patent No. 815,176 granted March 13,1906 to Keith, Erickson and Erickson, being modified, however, to adaptthe switch to operate in a system in which the central oflice apparatusis controlled by impulses over the two sides of the line in series thecircuits being also somewhat modified to adapt the switch to operate ina system embodying the principles of my in vention. This connector isprovided with two separate line relays 65 and 66 bridged across thetrunk line, which bridge is controlled by the back-bridge relays 67 and68. The circuit of the relay 66 is likewise controlled by the busy relay69, the circuit of which is in turn controlled by the slow acting relay198. This busy relay 69 does not close a locking circuit for itself whenenergized, as is usually the case in connectors of this type, but itsenergizing circuit is dependent on the ground on the connector bankcontact upon which the private wiper 71 is resting. The operation ofthis switch is controlled through the medium of the usual vertical androtary magnets 19A and 203. A ringer relay 73 is likewise provided,which is directly under the control of the operator at the cord circuitO. Likewise, the holding and release circuits of the switches employedin establishing connection with this connector, instead of beingcontrolled from this connector, are controlled directly by the relay 62at the operators board, one of said relays being associated with each ofthe selector switches F.'

For the purpose of supplying current for operating the central oiceapparatus and for talking purposes there is shown in the drawings abattery B having one terminal grounded at G.

A general description of the apparatus having been given it will now beexplained how the operator may extend a connection to the subscriber Awhose number is 220. In order to make this explanation clearer assumethat the subscriber A has set up a local call through the medium of hisline switch C, which is of the general type of individual switch shownin British Patent No. 26,301 of 1906 and of the particular type shown inBritishPatent No. 1419 of 1910, and a selector switch to which his lineswitch may have access. While this connection remains established aguarding ground will be established on the private conductor 206 fromthe said selector switch, which will hold the cut-off magnet 122 of theline switch C in energized position in a maniier well known in the art.A toll call coniing into the manual board over the conductors 53 and 54(Fig. 1) causes the line signal lamp 57 to glow. The operator, uponnoticing the line signal lamp 57 glowing, innnediately plugs the plug p2into the answering jack j2, which immediately causes the cut-olf relay56 to energize and cut off the line relay 55 and the line signal lamp57. The energizing circuit for the cut-o' relay 56 extends from groundG15 through the contact of springs 150, springs 151, sleeve of the plugand jack jz and the said cut-off relay 56 to battery B. A further resultof the energization of the relay 56 is to close a circuit through thevisual busy signals 58 at the different operatois positions that haveaccess to the trunk lines 53 and 54.- The operator now presses the keyK4 to connect her head set (not shown, but connected to the conductors153 and 1511) across the conductors 53 and 5&1. The operator, uponlearning that the subscriber at Lsubstation A is desired, inserts theplug p3 into the jack j* and operates the key K5 to bridge the callingdevice X across the conductors 155 and 156. The insertion of the plug p3into the jack j* connects the cord circuit O direct with the selector Fand closes a circuit through the relay 62. This latter circuit extendsfrom ground G16 through the resistance 157, sleeve of the plug p3,sleeve of the jack y"l and the relay 62 to battery B. The relay 62, uponenergizing, closes a circuit through the visual signal relays 63 at thevarious operators positions, thus showing that the trunk leading to theselector F is in use. The bridging of the calling device K across theconductors 155 and 156 causes the line relay 159 of the selectorI F toenergize over the following circuit. From ground G17 through the contactof springs 158 and 17 lower winding of the relay 159, springs 160 and161, springs 162, ring spring of jack jt, ring of the plug p3, conductor156, key K5, calling device X, key K5, conductor 155, tip of the plugp3, tip spring of jack j4, springs 163 and 1641 and the upper winding ofthe relay 159 to battery B. The relay 159, upon energizing, closes acircuit through the slow acting relay 165. The operator now operates hercalling device for the first digit 2, in response to which the selectorF raises its switch shaft and wipers in the manner described in theselector patent hereinbefore referred to, opposite the second row orlevel of bank contacts and then operates t0 find an idle trunk lineleading to a connector M. As soon as the shaft wipers 167, 168, and 169corne in contact with the idle bank contacts leading to the connector M,the switching relay 170 operates to disconnect the line relay 159 andextend the connection over the conductors 171 and 172 to the line relays65 and 66 ofthe connector M. The switching relay 170 is held energizedfrom the cord circuit O rather than from the connector switch ahead, asis usually the case with selectors of this type. The holdinncircuit forthe switching relay 170 extends from ground G18 through the contact ofsprings 173, springs 174i, springs 175, springs 176. springs 177 and 178 and the relay 170 to battery B. 1f the selector switch F should findall the contacts in the second level busy, the rotary magnet, upontaking its last rotary step, will open the contact of the springs 176and the springs 158 and 179 and close the contact of springs 180 and179. The opening of the springs 176 opens the circuit of the rotarymagnet 181 and allows the relay 182 to denergize. The closing of thesprings 180 and 179 gives the operator a special busy signal over a pathextending from ground G19 through one coil of the busy machine Q2 (onlythe induction coil of said busy machine being shown), contacts of thesprings 180 and 179, lower winding of the relay 159, springs 160 and161, over the heavy conductor to and through the operators head set(When she restores the key K5), over the heavy return conductor, springs163 and 164 and the upper winding of the relay 159 to battery B. Theoperator, upon hearing the busy signal, releases the connection andcalls again. Assuming that the selector F obtained connection with theconnector M, the relays and 66 immediately energize. The relay 66, uponenergizing, closes a circuit extending from ground G20 through thecontact of springs 186 and the relay 187 to battery B. The relay 187,upon energizing, prepares a circuit for the vertical magnet by closingthe springs188 and 189 and opens the circuit of the release magnet 190at the springs 189 and 191. A further result of the energization of therelay 187 is to close a locking circuit for itself, which circuitextends from ground G18 at 4the cord circuit O through the contact ofsprings 173, springs 174, springs 175, wiper 168, conductor 193, springs192, and the said relay 187 to battery B. The apparatus is now inreadiness to receive impulses for the second digit of the called number.

The operator now operates her calling de* vice for the second digit 2,whereby the line relay 65 operates to transmit two impulses through thevertical magnet 194 over a circuit extending from ground G21 through thecontact of springs 196 and 197, springs 189 and 188, relay 198, springs199, the vertical magnet 194 and the side switch wiper 201 to battery B.The vertical magnet 194 receives two impulses over this circuit andoperates to raise the switch wipers 70, 71 and 72 to a position oppositethe second level of bank contacts. The relay 198, which is included inseries with the vertical magnet, remains in its energized positionduring the entire time that impulses are being sent through it andoperates to close the circuit of the private magnet 202. After the lastimpulse is delivered, the relay 198 opens the circuit of the privatemagnet 202, which, upon denergizing, permits the side switch to advancefrom first to second position. The movement of the side switch wiper 201from first to second position transfers the battery connection from thevertical magnet 194 to the rotary magnet 203. The operator now operatesher calling device X for the last digit 0, in response to which theconnector line relay 65 operates to transmit ten impulses through theyrotary magnet 203 in series with the relay 198, whereby the shaftwipers are rotated onto the contacts of the desired line. The relay 198,upon denergizing, opens the circuit of the private magnet 202, theprivate magnet, however, does not denergize and step the side switch tothird position at this time because the private wiper 71 is resting upona grounded contact, which causes the following circuit to be closed assoon as the relay 198 dener gizes: from ground upon the bank contact 223(upon which the wiper 71 is resting, as it will be recalled that thesubstation A is in connection with a local selector switch), side switchwiper 208 (in second position), relay 69, springs 209 and 210 and theprivate magnet 202 to battery B. The magnet 202 is thus held energized,which holds the side switch locked in second position and opens thecircuit of the switching relay 211 at the springs 212. The relay 69,upon energizing, opens the circuit of the rotary magnet 203 at thesprings 199 to prevent a further rotation of the wipers and opens up oneside of the calling line at the springs 214. The engagement of thesprings 215 serves to close a circuit for the busy tone from the busymachine Q through the said springs, condenser 218, conductor 172 to andthrough the operators head set (when she restores the key K5 to normal),return conductor 171, springs 219 and 220 and the relay 65 to battery B.As soon as the operator hears the busy signal she operates the key K6 toconnect the special busy supervisory lamp 61 to the spring 220 of therelay 221. The operator may now go ahead and tend to other calls thatmay come into her position. As soon as the connection of the subscriberA with the other switches is released, the guarding potential will beremoved from the bank contact 223 upon which the wiper 71 is resting.The removing of the ground from the bank Contact 223 opens the circuitof the busy relay 69 and the private magnet 202. The private magnet,upon denergizing, allows the side switch to move from second to thirdposition. The relay 69, upon denergizing, removes the busy tone from theconductor 172 and closes a circuit through the relay 221 at theoperators cord circuit. This circuit extends from ground Gr23 throughthe relay 66, contact of springs 214, springs 225, conductor 172 andthrough the said coil 221return conductor 171, springs 219 and 220 andthe relay 65 to battery B. The relay 221, upon energizing, closes acircuit through the supervisory busy lamp 61 over a circuit extendingfrom ground G25 through the contact of springs 226 and 220',

springs of key K6 and the lamp 61 to battery B. The side switch wiper208 passing to third position, closes a circuit through thebridge-cut-otf coil 122 of the line switch C. This circuit extends fromground G2G, side switch wiper 208, private wiper 71, Contact 223 overthe conductor` 123 and the winding 122 to battery B. A further result ofthe side switch wiper 208 passing to thirdposition is the closing of acircuit through the relay 211, which, upon energizing, completes theconnection through to the substation A.

The operator, upon noticing the lamp 61 glowing, restores the key KG tonormal and presses the key K9. As soon as the key K9 is depressed, thecircuit through the line relay 65 is maintained, but the circuit throughthe line relay 66 is broken at the springs 243 and 2441 of the key K9.The denergization of the relay 66 closes a circuit through the ringingrelay 73. This circuit extends from ground G21 through the contact ofsprings 196 and 195, springs 227, relay 73 and the side switch wiper 201(in third position) to battery B. The relay 73, upon energizing,disconnects the callingline from the called line and bridges the ringingcurrent generator R2 vacross the called line. The operator now restoresthe key K" to normal, thus bridging the coil 221 again across the lineconductors 155 and 156, which causes the said relay to energize andclose a circuit through the supervisory lamp 59. As soon as the calledsubscriber answers, the back-bridge relays 67 and 68 are energized. Thesaid relays, upon energizing, disconnect the line relays 65 and 66 fromthe conductors 171 and 172 and connect the calling line with the calledline inductively through the windings of the repeating coil S. Thedisconnecting of the relays 65 and 66 from the conductors 171 and 172allows the relay 221 of the cord circuit to denergize, which, upondenergizing, opens the circuit of the supervisory lamp 59. The keys K7and KS of the cord circuit O are so arranged that the operator mayconnect her head set with either the calling or the called end of thecord circuit without connecting it with both ends at the same time.

As soon as the conversation is completed, the called subscriber, uponreplacing his receiver upon the switch-hook, allows the backbridgerelays 68 and 67 to denergize and again bridge the relays 65 and 66across the conductors 171 and 17 2, thus causing the supervisory relay221 to energize and close a circuit through the supervisory lamp 59. Assoon as the calling subscriber transmits a disconnect signal over theconductors 53 and 54, the relay 228 breaks the circuit of the cut-oli'relay 56 at the springs 150. However, the relay 56 does not denergize,for at the instant that the springs 150 separate, the shunt around therelay 229 is removed and the said relay 229 is cut in series with therelay 56. The relay 229, upon energizing, closes a circuit through thefront supervisory lamp 60 and permanently opens the shunt around itselfat the springs 151. The operator, receiving the disconnect sig nal,immediately removes the plug p2 from the jack t7'2 and the plug p3 fromthe jack jt Removing the plug p2 from the jack 7'2 opens the circuit ofthe relays 229 and 56. The relay 56 immediately denergizes and opens thecircuit of the visual busy signals 58 at the springs 230 and 231.Removing the plug p3 from the jack j4 opens the circuit of the relay 62,which, upon denergizing, opens the circuit of the visual busy signals 63at the springs 132 and also opens the circuit of the relays 170 and 187of the selector F and the connector M, respectively, at the springs 173.The relay 170, upon deenergizing, closes a circuit through the releasemagnet 233. The said circuit extends from ground G30 through the contactof the springs 235 and 236, springs 237, springs 238 and 239, off-normalsprings 234 and the release magnet 233 t0 battery B. The release magnet,upon energizing, releases the selector F in the same manner as describedin the selector patent referred to. The relay 187 of the connector M,upon deenergizing, closes a circuit through the release magnet 190. Thesaid circuit extends from ground G21 through the contact of springs 196and 197, springs 189 and 191, off-normal springs 240 and the releasemagnet l190 to battery B. The magnet, upon energizing, restores theswitch shaft and side switch wipers to normal position and its owncircuit is broken at the springs 240 when the shaft reaches its lowestposition.

It will thus be seen that I have provided a very eticient system and onein which the connector locks upon a busy line, and as soon as this linebecomes idle, the side switch is tripped so as to cut the connectionthrough to the desired line and at the same time a signal is fiashed atthe operators board, advising the operator of the fact that theconnection has been established with the called line, so that theoperator can then supply ringing current to the line to signal thesubscriber. It will furthermore be seen that the connector, instead ofbeing provided with the usual condensers in the talking conductors inorder to divide the same into calling and called branches, is providedwith a repeating coil, and, furthermore, that the front-bridge relays ofthe connector are disconnected from the talking circuit when the calledsubscriber answers by the operation of the back bridge relays, and inthis manner the amount of leakage across the line is greatly reduced.

lVhile I have thus illustrated and de scribed my invention in connectionwith one particular' type of automatic system and in connection withautomatic switches and toll apparatus of a particular character, itwill, of course, be understood that I do not wish to be limited to theexact construction shown and described, but that various changes andmodifications will readily suggest themselves to those skilled in theart and come within the spirit of my invention.

What I claim as my invention is:

l. In a telephone system, a manual switchboard, a subscribers line, anautomatic connector switch controllable from said switchboard to connectwith said line, a side switch in said connector movable to successivepositions in the operation of the same, means controlled by said sideswitch in one of its positions adapted to complete said connection, andmeans operated if said connection is attempted when the said line isbusy to lock said side switch in an intermediate position to render saidconnecting means inoperative, said locking means rendered ineffectivewhen the said line becomes idle, whereby the said side switch ispermitted to move to another position to render said connecting meansoperative to complete said connection.

2. In a telephone system, a manual switchboard, a subscribers line, anautomatic connector switch controllable from said switchboard to connectwith said line, a side switch in said connector movable to successivepositions in the operation of the same,4 means controlled by said sideswitch in one of its positions adapted to complete said connection,means operated if said connection is attempted when the said line isbusy to lock said side switch in an intermediate position to render saidconnecting means inoperative,

said locking means rendered ineffective when the said line becomes idle,whereby the said side switch is permitted to move to another position torender said connecting means operative to complete said connection, andasignal at the switchboard for indicating when said connection iscompleted.

3. In a telephone system, a manual switchboard, an operators head set atsaid board, a subscribers line, an automatic connector switchcontrollable from said switchboard to connect with said line, means insaid switch for automatically preventing the completion of suchconnection while the said line is busy and for giving the operator abusy signal,

means for` automatically completing such connection when the said linebecomes idle, and another signal at the switchboard for indicating whensaid connection is completed.

4;. In a telephone system, a manual switchboard, an operators head setat said board, a subscribers line, a trunk line extending from saidswitchboard to an automatic connector switch, said switch controllableover said trunk to connect with said' line,- contacts in said switch andmeans for closing them after the said line has been found to completeconnection thereto, means for preventing the closure of said contactswhen the said line is busy and until it becomes idle and for giving theoperator a busy signal, and another signal at the switchboard forindicating when said connection is completed.

5. In a telephone system, a manual switchboard, a subscribers line, anautomatic connector switch controllable from said switchboard to connectwith said line, a side switch in said connector movable to successivepositions in the operation of the same, means controlled by said sideswitch in one of its positions adapted to complete said connection,means operated if said connection is attempted when the said line isbusy to lock said side switch in an intermediate position to render saidconnecting means inoperative, said locking means ineffective when thesaid line becomes idle, whereby the said switch is permitted to move toanother position to rendersaid connecting means operative to completesaid connect1ona signal at said switchboard, and a relay for operatingsaid signal upon the completion of said connection.

6. In a telephone system, a manual switchboard, a subscribers line, anautomatic connector switch controllable from said switchboard to connectwith said line, means in said switch Jfor automatically preventing thecompletion of such connection while the said line is busy, means forautomatically completing such connection when the said line becomesidle, a `signal at said switchboard, and a relay for operating saidsignal upon the completion of said connection.

7 In a telephone system, a manual switchboard, a subscribers line, atrunk line eX- tending from said switchboard to an automatic connectorswitch, said switch controllable over said trunk to. connect with saidline, contact-sv in said switch and means for closing them after thesaid line has been found to complete connection thereto, means forpreventing the closure of said contacts when the said line, is busy anduntil it 4becomes idle, a signal at said switchboard,

and a relay operated over said` trunkv line to operate said signal uponthe completion of said connection.

8. In a telephone system, a manual switchboard, a subscribers line, atrunk `line eX- tending from said switchboard to an automatic connectorswitch, a cord circuit at said switchboard having access to said trunkline, means in said cord circuit for operating said connector switch toconnect with said line, means in said switch for. automaticallypreventing the com letion of such connection, while the said ine isbusy, and means in said switch for automatically completing suchconnection when the said line becomes idle, and a visual signal at saidswitchboard 'for indicating a completion of said connection.

9. In a telephone system, a manual switchboard, a subscribers line, atrunk line extending from said switchboard to an automatic connectorswitch, a cord circuit at said switchboard having access to said trunkline, an operators head set at said cord circuit, means in said cordcircuit for operating said connector switch to connect with said line,means in said switch for automatically preventing the completion of suchconnection while the said line is busy and for giving the operator abusy signal, means in said switch for automatically completing suchconnection when the said line becomes idle, and another signal in saidcord circuit for indicating when said connection is completed.

10. In a telephone system, a manual switchboard, a subscribers line, atrunk line extending from said switchboard to an automatic connectorswitch, a cord circuit at said switchboard having access to said trunkline, means in said cord circuit tor operating said connector switch toconnect with said line, means in said switch for automaticallypreventing the completion of such connection while the said line isbusy, means in said switch for automatically completing such connectionwhen the said line becomes idle, a signal in said cord circuit. and arelay operated over said trunk line to operate said signal upon thecompletion of said connection.

11. In a telephone system, a manual switchboard, a subscribers line, atrunk line extending `from said switchboard to an automatic connectorswitch, a cord circuit at said switchboard having access to said trunkline, means in said cord circuit for operating said connector switch toconnect with said line, means in said switch for automaticallypreventing the completion of such connection while the said line isbusy, and means in said switch for automatically completing suchconnection when the said line becomes idle, a pair of signals in saidcord circuit, one signal for indicating when said connection iscompleted and the other signal for indicating the response of asubscriber on said line.

12. In a telephone system, a manual switchboard, a subscribers line, atrunk line extending from said switchboard to an automatic connectorswitch, a cord circuit at said switchboard having accessto said trunkline, means in said cord circuit for operating said connector switch toconnect with said line, means in said switch for automaticallypreventing the completion of such connec tion while the said line isbusy, meansin said switch for automatically completing suchy connectionwhen the saidline becomes idle, a pair of signals in said cord circuit,one signal for indicating when said connection is completed and theother signal for indicating the response of a subscriber on said line,and a common controlling relay :tor said signals operated over saidtrunk line.

13. In a telephone system, a manual switchboard, a subscribers line, atrunk line extending from said switchboard to an automatic connectorswitch', a cord circuit at said switchboard having access to said trunkline, means in said cord circuit for operating said connector switch toconnect with said line, means in said switch for automaticallypreventing the completion of such connection while the said line isbusy, means in said switch for automatically completing such connectionwhen the said line becomes idle, a pair of signals in said cord circuit,one signal for indicating when said connection is completed and theother signal for indicating the response of a subscriber on said "line,a common controlling relay for said signals operated over said trunkline, and a manually operated key for shifting the control of said relaytromone signal to the other.

14. In a telephone system, a calling and a called line, an automaticconnector switch, a repeating coil associated with said switch forrepeating talking current between said lines, means for extending thecalling line to said switch, a relay bridge connected across the callingline when so extended, said bridge adapted to control said switch toconnect one winding of said repeating coil with the called line, and arelay bridge across the called line when so connected, said last bridgeoperable upon the response of the called subscriber for disconnectingsaid first relay bridge and for substituting the other winding of saidrepeating coil therefor, said other winding of the repeating coil in acontinuous metallic bridge across the conductors of the calling lineduring talking.

15. In a telephone system, a manual switchboard, a subscribers line, atrunk line terminating in a connector "switch, a controlling relay forsaid switch normally connected to said trunk line, said relaycontrollable from said switchboard for operating said switch to connectwith said subscribers line, a repeating coil for repeating talkingcurrent between said lines, a relay bridge across the said subscribersline when so connected, and means controlled by said bridge over saidsubscribers line :tor disconnecting said controlling relay and forconnecting the said trunk line and the said subscribers line by way ofsaid repeating coil, one of the windings of said repeating coil being ina continuous metallic bridge across the conductors ofsaid trunk line.

16. In a telephone system, a manual switchboard, a subscribers line, atrunk line terminating in a connector switch, a controlling relay forsaid switch normally connected to said trunk line, said relaycontrollable from said` switchboard for operatingl said switch toconnect with said subscribers line, a repeating coil for repeatingtalking current between said lines, a relay bridge across 'the Saidsubscribers line when so connected, means controlled by said bridge oversaid subscribers line for disconnecting said controlling relay and forconnecting the said trunk line and the said subscribers line by way ofsaid repeating coil, one of the windings of said repeating coil being ina continuous metallic bridge across the conductors of said trunk line,and means controlled from said switchboard for maintaining said switchin operated )osition after said controlling relay has heen disconnected.

17. In a telephone system, a subscribersV line, an automatic connectorswitch adapted to establish connection therewith, a trunk line, meansfor controlling said switch over two sides of said trunk line in series,means for locking said switch on said subscriber-s line when saidsubscribers line is busy without extending the connection through tosaid line, and means for automatically completing said connection whensaid subscribers line is again idle.

18. In a telephone system, a subscribers line, an automatic connectorswitch adapted to establish connection therewith, a trunk line, meansfor controlling said switch over two sides of said trunk line in series,means for locking said switch on said subscribers line when said line isbusy without eXtending the connection througl'l to said line, means forautomatically completing said connection when said subscribers line isagain idle, a signal7 and means for operating said signal whenconnection is completed with the subscribers line.

19. In a telephone system, a subscribers line, an operators board, anoperato1"s head set at said board, means including an automaticconnector switch for establishing a connection from said board to saidline, means for locking said connector switch on said line if the sameis busy and for giving the operator a busy signal without establishing atalking connection between said board and said line, means forautomatically cutting said connection through when said line is nolonger busy, another signal at said board, and means for operating saidother signal to inform said operator when said connection is cut throughto the line.

20. In a telephone system, a subscribers line, an operators board, meansincluding an automatic switch for establishing connection from saidboard to said line, a side switch having three operative positions,means for locking said side switch in second position when saidconnector establishes connection with a busy line, and means for causingsaid side switch to pass to third position as soon as said line is nolonger busy.

21. In a telephone system, a subscribers line, an operators board, meansincluding an automatic switch for establishing connection from saidboard to said line, a side switch having three operative positions,means for locking said side switch in second position when saidconnector establishes connection with a busy line, means for causingsaid side switch to pass to third position as soon as said line is nolonger busy, and means i'or signaling said operator when said sideswitch is tripped to third position.

`Signed by me at Chicago, Cook county, Illinois, this 24th day of Feb.,1916.

BERNARD D. WILLIS.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. C.

